Response Spectra for Multicomponent Structural Analysis

2006 ◽  
Vol 22 (1) ◽  
pp. 85-113 ◽  
Author(s):  
Oscar A. López ◽  
Julio J. Hernández ◽  
Ricardo Bonilla ◽  
Aura Fernández
Keyword(s):  
Structural Analysis ◽  
Principal Components ◽  
Vertical Component ◽  
Response Spectra ◽  
Vertical Axis ◽  
Period Range ◽  
Vibration Period ◽  
Intermediate Period ◽  
Near Fault ◽  
Far Fault

This paper aims to investigate the response spectra characteristics of the principal components of seismic motion, which are required for accurate multicomponent structural analysis. Mean spectra were determined for the three principal uncorrelated acceleration components for an ensemble of 97 earthquake records. The average inclination of the quasi-vertical component from the vertical axis is found to be 11.4°, with a standard deviation of 9.9°. The ratio of the minor and the major quasi-horizontal spectra varies between 0.63 and 0.81, which are lower than the value of 1 commonly used in design codes. Greater differences are found for near-fault motions in the intermediate-period range. The ratio of the quasi-vertical and the major quasi-horizontal spectra varies between 0.34 and 0.69 for far-fault and between 0.3 and 1.33 for near-fault motions, depending on vibration period. Smoothed spectra of the three principal components that can be used in modern multicomponent structural analysis methods are presented.

Drift Spectrum vs. Modal Analysis of Structural Response to Near-Fault Ground Motions

2001 ◽  
Vol 17 (2) ◽  
pp. 221-234 ◽  
Author(s):  
Anil K. Chopra ◽  
Chatpan Chintanapakdee
Keyword(s):  
Earthquake Engineering ◽  
Response Spectrum ◽  
Ground Motions ◽  
Structural Response ◽  
Response Spectra ◽  
Engineering Practice ◽  
Drift Spectrum ◽  
Combination Rules ◽  
Near Fault ◽  
Far Fault

A new measure of earthquake demand, the drift spectrum has been developed as an adjunct to the response spectrum, a central concept in earthquake engineering, in calculating the internal deformations of a structure due to near-fault ground motions with pronounced coherent pulses in the velocity and displacement histories. Compared in this paper are certain aspects of the elastic structural response to near-fault and far-fault ground motions. It is demonstrated that (1) the difference between drift and response spectra are not unique to near-fault ground motions; these differences simply reflect higher-mode response, which is larger due to near-fault ground motions; (2) response spectrum analysis (RSA) using existing modal combination rules can provide an estimate of structural response that is accurate to a useful degree; (3) these modal combination rules are similarly accurate for near-fault and far-fault ground motions although the underlying assumptions are not satisfied by near-fault excitations; and (4) RSA is preferable over the drift spectrum in computing structural response because it represents standard engineering practice and is applicable to a wide variety of structures.

scholarly journals Influence of near-fault characteristics on inelastic response of multi-storey building with intensity measurement analysis

2021 ◽  
Vol 73 (11) ◽  
pp. 1081-1092
Keyword(s):  
Safety Performance ◽  
Vibration Period ◽  
Near Fault ◽  
Intensity Measurements ◽  
Measurement Analysis ◽  
Frame Buildings ◽  
Concrete Building ◽  
Inelastic Responses ◽  
Far Fault ◽  
Storey Building

This study is presented to achieve three objectives: (1) to compare between the inelastic responses of buildings under near and far fault excitations, (2) to investigate the effect of the pulse to structural period ratio, and (3) to evaluate a set of intensity measurements (IMs) in terms of near fault (NF) earthquakes. A real reinforced concrete building with 35 storeys is analysed in the scope of the first and second objectives, whereas the third objective involves three general-frame buildings consisting of 6, 13, and 20 storeys. Results show that the NF excitation can drive the building to exceed its life safety performance level. Furthermore, the accuracy of the IM highly depends on the vibration period of the building and the function used to calculate the IM.

The Vertical and Horizontal Spectra of Near-Fault Ground Motions

2012 ◽  
Vol 204-208 ◽  
pp. 3335-3339
Author(s):  
Jiang Yin ◽  
Xian Yan Zhou ◽  
Guo Jing He
Keyword(s):  
Ground Motions ◽  
Response Spectra ◽  
Vertical Acceleration ◽  
Period Range ◽  
Seismic Reliability ◽  
Design Spectrum ◽  
Near Fault ◽  
Seismic Design Code ◽  
Short Period ◽  
Near Fault Earthquakes

Based on the horizontal and vertical components of a set of 30 acceleration records obtained from 10 near-fault earthquakes, the horizontal and the vertical response spectra are established, and have been compared with each other in this study. Statistical analyses show that, for the selected 30 acceleration records, the maximum mean of vertical acceleration spectra is slightly higher than which of horizontal acceleration spectra. That means the near-fault earthquake really have significant vertical effect. Consulting the domestic and international research achievement, the normalized near-fault design spectrum adapted to Chinese seismic design Code (GB50011-2010) is established in horizontal direction. The results show that, within short period range, the horizontal near-fault design spectrum obtained in this paper is obviously higher than which derived from Chinese seismic code. Subsequently, the spectra of horizontal components for the selected 30 records are each scaled to match the horizontal near-fault design spectrum at two periodic points of 1.0 and 1.5 sec respectively, and the corresponding vertical spectra are scaled with the horizontal spectra at the same time. The scaled results reveal that the vertical spectra have much higher discretion than horizontal spectra, hence the study in this paper could initiates the research interest to a new aspect concerned with the randomness of vertical spectra for near-fault ground motions, which would affect the seismic reliability of structures significantly.

Effects of Fling Step and Forward Directivity on Seismic Response of Buildings

2006 ◽  
Vol 22 (2) ◽  
pp. 367-390 ◽  
Author(s):  
Erol Kalkan ◽  
Sashi K. Kunnath
Keyword(s):  
Seismic Response ◽  
Ground Motions ◽  
High Amplitude ◽  
Moment Frames ◽  
Steel Moment Frames ◽  
Damage Potential ◽  
Near Fault ◽  
Forward Directivity ◽  
Fling Step ◽  
Far Fault

This paper investigates the consequences of well-known characteristics of near-fault ground motions on the seismic response of steel moment frames. Additionally, idealized pulses are utilized in a separate study to gain further insight into the effects of high-amplitude pulses on structural demands. Simple input pulses were also synthesized to simulate artificial fling-step effects in ground motions originally having forward directivity. Findings from the study reveal that median maximum demands and the dispersion in the peak values were higher for near-fault records than far-fault motions. The arrival of the velocity pulse in a near-fault record causes the structure to dissipate considerable input energy in relatively few plastic cycles, whereas cumulative effects from increased cyclic demands are more pronounced in far-fault records. For pulse-type input, the maximum demand is a function of the ratio of the pulse period to the fundamental period of the structure. Records with fling effects were found to excite systems primarily in their fundamental mode while waveforms with forward directivity in the absence of fling caused higher modes to be activated. It is concluded that the acceleration and velocity spectra, when examined collectively, can be utilized to reasonably assess the damage potential of near-fault records.

scholarly journals Influence of Elastomeric Bearings in Tension on the Seismic Performance of Base-Isolated r.c. Buildings

2020 ◽  
Vol 11 (1) ◽  
pp. 82
Author(s):  
Fabio Mazza ◽  
Mirko Mazza
Keyword(s):  
Base Isolation ◽  
Nonlinear Models ◽  
Vertical Component ◽  
Computer Code ◽  
Nonlinear Phenomena ◽  
Isolation System ◽  
Elastomeric Bearings ◽  
Near Fault ◽  
Base Isolation System ◽  
Near Fault Earthquakes

Elastomeric bearings are commonly used in base-isolation systems to protect the structures from earthquake damages. Their design is usually developed by using nonlinear models where only the effects of shear and compressive loads are considered, but uncertainties still remain about consequences of the tensile loads produced by severe earthquakes like the near-fault ones. The present work aims to highlight the relapses of tension on the response of bearings and superstructure. To this end, three-, seven- and ten-storey r.c. framed buildings are designed in line with the current Italian seismic code, with a base-isolation system constituted of High-Damping-Rubber Bearings (HDRBs) designed for three values of the ratio between the vertical and horizontal stiffnesses. Experimental and analytical results available in literature are used to propose a unified nonlinear model of the HDRBs, including cavitation and post-cavitation of the elastomer. Nonlinear incremental dynamic analyses of the test structures are carried out using a homemade computer code, where other models of HDRBs considering only some nonlinear phenomena are implemented. Near-fault earthquakes with comparable horizontal and vertical components, prevailing horizontal component and prevailing vertical component are considered as seismic input. Numerical results highlight that a precautionary estimation of response parameters of the HDRBs is attained referring to the proposed model, while its effects on the nonlinear response of the superstructure are less conservative.

Seismic Response Analysis of CFST Arch Bridge Considering Input Earthquake Characteristics

2011 ◽  
Vol 255-260 ◽  
pp. 962-966
Author(s):  
Fan Xing ◽  
Lin Zhao ◽  
Ya Zhe Xing
Keyword(s):  
Seismic Response ◽  
Research Result ◽  
Steel Tube ◽  
Response Analysis ◽  
Vibration Period ◽  
Arch Bridge ◽  
Near Fault ◽  
Long Span ◽  
Cfst Arch Bridge ◽  
Out Of Plane

In view of huge destructibility of the near-fault ground motions, structures with long natural vibration period are liable to fall into nonlinear reaction stage. Based on a full understanding of the near-fault seismic spectrum characteristics, the out-of-plane seismic response of a long span concrete-filled steel tube (CFST) arch bridge was studied in depth, and the research result could offer a reference for near-fault aseismic design.

Navigating in a volumetric world: Metric encoding in the vertical axis of space

2013 ◽  
Vol 36 (5) ◽  
pp. 546-547 ◽  
Author(s):  
Theresa Burt de Perera ◽  
Robert Holbrook ◽  
Victoria Davis ◽  
Alex Kacelnik ◽  
Tim Guilford
Keyword(s):  
Spatial Information ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Vertical Component ◽  
Vertical Axis ◽  
Orthogonal Axis ◽  
Experimental Protocols ◽  
Three Dimensional Space ◽  
The Way

AbstractAnimals navigate through three-dimensional environments, but we argue that the way they encode three-dimensional spatial information is shaped by how they use the vertical component of space. We agree with Jeffery et al. that the representation of three-dimensional space in vertebrates is probably bicoded (with separation of the plane of locomotion and its orthogonal axis), but we believe that their suggestion that the vertical axis is stored “contextually” (that is, not containing distance or direction metrics usable for novel computations) is unlikely, and as yet unsupported. We describe potential experimental protocols that could clarify these differences in opinion empirically.

Failure Mechanism of Reinforced Concrete Rib Arch Bridge under Near-Fault Earthquakes

2011 ◽  
Vol 90-93 ◽  
pp. 940-945
Author(s):  
Wen Jun Gao ◽  
Guang Wu Tang ◽  
Yi Da Kong
Keyword(s):  
Reinforced Concrete ◽  
Nonlinear Response ◽  
Plastic Hinge ◽  
Seismic Damage ◽  
Arch Bridge ◽  
2008 Wenchuan Earthquake ◽  
Near Fault ◽  
Pulse Type ◽  
Near Fault Earthquakes ◽  
Far Fault

A typical reinforced concrete rib arch bridge was chosen to investigate its nonlinear response to near-fault ground motions recorded in 2008 Wenchuan earthquake. Results showed that significant seismic damage may occur, maximum demands were higher for near-fault records having forward directive than far-fault motions, and the rotational capacity of rib plastic hinge is not enough for the large compression force of arch rib. While backward-directivity motions, typically do not exhibit pulse-type motions, only have medium seismic damage to the arch bridge.

scholarly journals Improving the Seismic Behavior of Symmetrical Steel Structures Under Near-Field Earthquake Using a Base Isolation Method Lead Rubber Bearing Isolator

2016 ◽  
Vol 10 (7) ◽  
pp. 10
Author(s):  
Musa Mazji Till Abadi ◽  
Behnam Adhami
Keyword(s):  
Seismic Isolation ◽  
Retaining Wall ◽  
Vertical Component ◽  
Steel Structures ◽  
Vertical Movements ◽  
Near Fault ◽  
Rubber Bearing ◽  
Lead Rubber Bearing ◽  
Fixed Base ◽  
Near Fault Earthquakes

<p>In this study, the function and application of seismic isolation system through lead rubber bearing isolator (LRB) in near-fault earthquakes are compared with fixed-base structures. As a result of their high frequency content, near-fault earthquakes impose huge energy on structures and cause severe damages. One of the appropriate solutions for this issue is the use of LRB which decreases the amount of imposed energy on structures. To improve the function of isolated structures under the near-fault earthquakes, isolators are designed in a way to tolerate the vertical component of earthquakes. To this purpose, we limit the displacements due to the horizontal movements of isolator through Gap spring which acts as a retaining wall and prevent shocks to other buildings. Moreover, this approach decreases the vertical movements of isolators and indirectly improves their behavior. In the current study, three buildings with four, eight, and 12 floors (with and without gap spring) were included. Isolators were manually designed in accordance with AASHTO-LRB regulations and the behaviors of both isolators and buildings are considered non-linear. Then we analyzed and compared the amount of energy, displacement, and acceleration of structure at the center of roof. The results indicated a significant decrease in the results of base shear, the acceleration of roof center, floors drift and energy imposed on the structure in the isolated system in comparison with the fixed-base structure.</p>

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